How this river rock calculator works
River rock sells by the ton, and rounded stone runs about 1.35 tons per cubic yard — slightly lighter than crushed because round rocks don't pack. Volume, density, allowance:
tons = yd³ × 1.35 × (1 + allowance%) → rounded up to ¼ ton
Worked example: how much river rock for a 15 × 10 bed
150 ft² at 3 in is 37.5 ft³ — 1.39 yd³. With 10% allowance that's 2.06 tons, so you order 2.25 tons (about $146 at $65/ton) or 1.75 yd³ bulk. The same bed in bags would take 83 of them at roughly $581 — decorative rock is the classic bulk-delivery win.
How much does a ton of river rock cover?
| Depth | Coverage |
|---|---|
| 2 in | ≈ 120 ft² |
| 3 in | ≈ 80 ft² |
| 4 in | ≈ 60 ft² |
Depth rule: lay rock about twice as deep as its largest diameter — the chips above cover ¾ in pebbles (2″), 1–3 in rock (3″), and larger stone (4″).
River rock FAQ
How much river rock do I need for 150 square feet?
At the typical 3 in depth, a 15 × 10 ft bed takes 2.25 tons (1.39 yd³ exact, ordered as 1.75 yd³ bulk) — about $146 delivered at $65/ton, versus roughly $581 as 83 bags. Bulk wins on anything bigger than a strip.
How many tons of river rock are in a cubic yard?
About 1.35 tons for common 1–3 in river rock, and closer to 1.4 for small ⅜–¾ in stone that packs tighter. Your supplier weighs the load; these figures size the order.
How deep should river rock be?
Twice the diameter of the largest stone: 2 in of depth for ¾ in pebbles, 3 in for 1–3 in rock, 4 in and up for anything fist-sized. Too shallow and the fabric or soil shows; too deep just buries money.
How much does a ton of river rock cover?
About 80 ft² at 3 in deep, 120 ft² at 2 in, and 60 ft² at 4 in. The live coverage line under the drawing tracks your depth and material.
Should I put landscape fabric under river rock?
Yes — a woven fabric keeps rock from sinking into soil and makes eventual weeding survivable. Overlap seams 6 in, pin it, then place rock gently; skip plastic sheeting, which traps water.
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